In recent years, nearly all electronic devices have been reduced in size and weight, in particular portable electronic devices such as cellular telephones, two-way radios, laptop computers, personal digital assistants (PDAs). This advancement has been made possible, in part, by the development of new battery chemistries such as nickel-metal hydride, lithium ion, zinc-air, and lithium polymer that enable larger amounts of power to be packaged in a smaller container. Although these new batteries are a tremendous advancement over the previous generations of batteries, they still suffer from the need for sophisticated charging regimens and the slow charging rates. Some have sought to replace electrolytic batteries with fuel cells that catalytically convert a hydrogen molecule to hydrogen ions and electrons, and then extract the electrons through a membrane as electrical power, while oxidizing the hydrogen ions to H2O and extracting the byproduct water. The tremendous advantage of fuel cells is the potential ability to provide significantly larger amounts of power in a small package, as compared to a battery. In general, the fuel cell technologies can be divided into three categories, namely, fuel cells employing compressed hydrogen gas as fuel, fuel cells employing methanol reformates as fuel, and direct methanol fuel cells. Methanol is more attractive to consumers than gaseous hydrogen, as it is more readily available and can be more easily stored. In direct methanol fuel cells, the methanol is generally mixed with water and presented to the membrane electrode assembly (MEA) where it is converted to hydrogen and carbon dioxide. The methanol must be mixed with water in order to facilitate the catalytic reaction and to prevent the methanol from migrating through the polymer membrane in the MEA and crossing over from the anode side to the cathode side. Although the theoretical ratio of water to methanol is one-to-one (mole basis), in practice the water is mixed with methanol in amounts from 50% to 98% (by volume) in order to prevent crossover.
Polymer electrode membrane (PEM) fuel cells operate most efficiently at temperatures between 60° C. and 80° C. In prior art systems, the mixture of water and methanol is heated prior to introducing it to the MEA to keep the water from condensing. However, heating the fuel/water mixture creates a series of problems. The heated fuel stream further heats the fuel cell and increases the operating temperature of the cell, and increased operating temperature tends to dehydrate the MEA. It would be a significant contribution to the art if there were a method of supplying humidified methanol that did not heat either the water or the methanol.